166 ADEPHAGA. [IJ IJphljdrUS. 



the Old "World (Africa, especially Madagascar, Japan, Australia, &c.) ; 

 but probably this number will be largely increased ; two only are Euro- 

 pean, one of which is very common in the centre and south of England ; 

 the second species, H. varier/atus, has been reputed as indigenous, but 

 the single specimen on which it rested (supposed- to have been taken in 

 Lancashire or Cheshire) was far too doubtful to secure its admittance 

 into our lists, especially as the species appears to be almost entirely 

 confined to Northern Africa and Southern Europe. 



The larva of H, ovatus is figured by Schiodte (ii., PI. v., Fig. 1) : it corresponds so 

 closely with Westwood's description of the larva of Noterus referred to above (p. 160), 

 that it is possible that some mistake may have arisen ; the very peculiar shape of the 

 head is exactly repeated ; the larva (excluding the head) has the shape of a rather elongate 

 peg-top ; the eighth segment is produced into a long point, and bears two moderately 

 long setose cerci, which start from its base ; it is of a luteous colour with somewhat 

 varied dark markings : as a rule the dorsal segments are dark fuscous with the 

 prothorax (except front), and the two first and two last segments of abdomen light. 



H. ovatus, L. {fernigineus, L., $). Broad oval, very convex on both 

 the upper and under sides, ferruginous, with the elytra darker, reddish 

 at base and sides ; male with the upper side shining, thickly, strongly, 

 and irregularly punctured, with anterior and intermediate pairs of legs 

 tliickened and the tarsi dilated ; female dull, obsoletely punctate. 

 Long. 4-^, lat. 3 mm. 



Ponds and ditches ; very common throughout the central and southern counties 

 of England and Wales; less common further north, although widely distributed; 

 Scotland, very local, only recorded from the Solway district; Ireland, Portmaruock, 

 Armagh, &c., and probably common. 



The vnrierjatns ? of Bteph. ]Mand. ii. 45 is a variety of this insect, and 

 has nothing to do with H. varier/atus, Aube. 



CCEIiAI^SUS, Thomson. (Ili/grofus, Steph. pars.) 



This genus comprises about forty species, which are chiefly found in 

 Europe, Asia, and North America ; they differ very widely in form and 

 general appearance, one division of our species being of very short and 

 convex form, and the other l)eing much longer, wider, and more 

 depressed and apparently quite different : it is probable that one of the 

 species, H. decoratus, will have to be separated off as a distinct genus, 

 for it possesses, although obscurely, the chief character of Hydroporus, 

 viz. the connection of the intercoxal process of the metasternum with 

 the mesosternal fork ; for the present, however, it is best to leave it with 

 the seemingly allied species ; the chief generic character appears to be 

 the free and abrupt ligida on the imier face of the elytra. 



The larva and pupa of C. parallelogrammus are figured by Schiodte (ii., PI. iv., 

 Fig. 13, 14) : it is of a very peculiar torpedo-like form, being broad and convex with 

 the head very large and triangular and produced into a broad horn ; the thorax is 

 about as broad as the base of the head, subquadrate, somewhat transverse with the 

 angles rounded ; the meso- and meta-tborax and the first five abdominal segments are 

 of iibout equal length, all being very narrow, the second abdominal segment being the 



